That should be easy ball to attack for a pro. Their serve percentage is high because they serve 1000 balls a day. If you see a pro over and over
Serving in the middle of the box it's because he or she is struggling with a serve that day or with return of his or her opponent.
Middle ball = no advantage but to start a point.

Its amazing they could place the ball more than 3 feet before the service line.

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You should see the full highlights of the match, a couple of points after this one Federer hit another second serve at Sampras and it touched the line and again Sampras was handcuffed. A lot of confidence in that second serve.

Most top players can place 95% of their kick serves into the 3 quatrants on the opponent's service box. They can choose whichever, depending on the return strengths and weaknesses of the opponents. I'll have to qualify that, the top players who CARE to serve well. Some don't, and spend the time on conditioning and groundie practice.
Lots of long tall guys can handle wide twists and kicks, and lots of short stocky guys can handle body shots with aplomb.
But very few returners can handle both.
Once you spot the weakness, you can hold it in your mind and use it on a critical point.
And serving within 3' of the service line, IN every time, is a simple 4.5 level trait.

Don't forget at ATP level the kick serves are 80mph+, and could kick as high as 6'5 or more at the base line. And together with some side spin, the landing spot is just a byproduct of insuring the ball being in.
There are many return winners but I have to say most 2nd serves are good enough to give some ground for the server. Unlike a lot of 4.0 2nd serves at 50mph or less, many can be smacked right back.